Product and process

ABSTRACT

Novel fasciated yarns for the production of crepe fabrics are prepared from a combination of fibers of which from 1 to 40 percent by weight have an average shrinkage that is at least 5 percent above that of the average of the remaining fibers. These yarns exhibit a yarn shrinkage differential, Delta Syarn, of at least 5 percent and a standard deviation, sigma , of at least 2.8 in short-term shrinkage variability.

llnited States Patent 1 Csok et a1.

[54] PRODUCT AND PROCESS [75] Inventors: Tibor Csok, Chadds Ford, Pa.; Karl Franz, Wilmington, Del.

[73] Assignee: E. I. du Pont de Nemours and Company, Wilmington, Del.

[22] Filed: Feb. 23, 1971 [21] App]. No.2 118,032

[52] US. Cl. ..57/140 BY, 57/144, 57/157 F [51] Int. Cl ..D0 2g 1/20, D02g 3/04, D02g 3/24 [58] Field of Search ..57/140 R, 140 BY, 57/144, 77.3, 77.33, 157 R, 157 TS, 157 MS,

[5 6] References Cited UNITED STATES PATENTS Maerov et al. ..57/140 BY Field ..57/140 BY X Nakayama et al ..57/140 BY 11] 3,732,684 51 May 15,1973

3,079,746 3/1963 Field ..57/77.33 X 3,302,385 2/1967 Ruddell et al..... ..57/157 MS 3,120,095 2/1964 Guthrie et al..... ..57/140 BY UX 3,248,771 5/1966 l-litomi et al. ..57/157 MS X 3,388,547 6/1968 Koga et al. ..57/140 BY X 3,416,302 12/1968 Knospe ..57/140 BY 3,439,490 4/1969 Tarkington et a1... .....57/l40 BY 3,445,995 5/1969 Bell et a1 ..57/77.3 X

Primary Examiner-Donald E. Watkins Attorney S01 Schwartz 57 1 ABSTRACT Novel fasciated yarns for the production of crepe fabrics are prepared from a combination of fibers of which from 1 to 40 percent by weight have an average shrinkage that is at least 5 percent above that of the average of the remaining fibers. These yarns exhibit a yarn shrinkage differential, AS of at least 5 percent and a standard deviation, 0', of at least 2.8 in short-term shrinkage variability.

9 Claims, 2 Drawing Figures FIG. I

PATENTED HAY 1 5 m5 FIG.2

INVENTORS TIBOR C 1 PRODUCT AND PROCESS BACKGROUND Crepe broadwoven fabrics are conventionally prepared from yarn having a twist on the order of 60 turns per inch (24 turns per cm.) or higher, whereby the yarn undergoes torsional buckling to produce a crepe effect in the fabric. Crepe fabrics produced in this way normally exhibit a hard, bitey hand owing to the high degree of twist in the yarn. Other crepe fabrics have been prepared by prior art processes from composite yarn in which a high-shrinkage fiber component and a lowshrinkage fiber component are twisted together to form the composite yarn. Such yarns are somewhat similar to composite, high-low shrinkage yarns suitable for the production of bulky fabrics.

Because crepe fabrics are inherently non-uniform in character, one problem which arises in their manufacture is to maintain a constant degree of non-uniformity, so that portions of the fabric produced will not appear to have only a low degree of crepe in some areas while exhibiting a high degree of crepe in other areas of the same fabric. The development of novel and distinctive crepe fabrics has also represented a challenge to the textile industry.

SUMMARY OF THE INVENTION In accordance with the present invention, a fasciated yarn is prepared from a sliver of discontinuous organic textile fibers of mixed shrinkage, wherein 1 to 40 percent by weight of the fibers are high-shrinkage fibers, the remainder being low-shrinkage fibers. By highshrinkage fibers it is meant that such fibers exhibit a shrinkage that is greater than that shown by the lowshrinkage fibers. It is not intended to imply that the fibers must shrink greatly in the absolute sense or that the low-shrinkage" fibers shrink little if at all. The average percent shrinkage of the high-shrinkage fibers should be at least equal to 5 percent plus the average percent shrinkage of the low-shrinkage fibers. The product is a novel fasciated yarn exhibiting a yarn shrinkage differential (as defined below) of at least 5 percent and having a variable lengthwise shrinkage, measured on successive 0.2-inch (0.5-cm.) segments; the standard deviation of shrinkage in the segments being at least about 2.8. Excellent fabrics having a crepe appearance of distinctive texture are produced from the yarn product. The development of crepe in these fabrics is unusual, because the crepe is not produced by high twist as with conventional crepe yarns, and does not involve yarn prepared by twisting together of separate high-shrinkage and low-shrinkage components. Surprisingly, the fabrics produced from these yarn products can also be finished flat, heat-set at high temperatures and hot calendered to produce smooth fabrics, free of the crepe effect, if desired.

DESCRIPTION OF THE DRAWING FIG. 1 is a schematic of a portion of the fasciated yarn of the invention demonstrating the general principles thereof. FIG. 1 includes three short segments wherein the core fibers are not tightly restrained by surface wrappings.

FIG. 2 is a schematic of the yarn of FIG. 1 after shrinking. The segments A, B, C and D correspond to the segments identified by the same letters in FIG. 1.

In FIG. 1 discontinuous organic textile core fibers 10 are bound together by surface wrappings of discontinuous organic textile fibers l1 twisted tightly about the bundle of core fibers as an irregular helical wrapping. By irregular is meant that along the length of the yarn, the helical wrap may appear in separate sections which may vary in helix angle. Fibers in the core portion are of mixed shrinkage as discussed in detail below. It will be understood that individual fibers may originate in (and be part of) the core portion of the yarn and terminate in (and also be part of) the wrapping and vice versa.

FIG. 2 represents the yarn of FIG. 1 which has been shrunk. As the higher shrinkage component fibers 13 of the core contract, the lower shrinkage component fibers 12 bloom in bulky segments A, B and D, where the core fibers are not restrained by surface wrappings. The ratio of high-shrinkage to low-shrinkage fibers in individual segments of the core varies randomly, which causes segments such as B to contract somewhat more than segments such as A. Segment C on the other hand, represents a bundle of core fibers 10 that have been shrunk but which bundle lacks bloom because of restraint by the surface wrappings 11.

DESCRIPTION OF THE PREFERRED EMBODIMENT In its preferred embodiment, this invention provides: a novel fasciated yarn comprising a core of discontinuous organic fibers bound together by discontinuous organic surface fibers disposed as a helical wrapping around the core, said yarn exhibiting a yarn shrinkage differential of at least 5 percent and a standard deviation of at least 2.8 in short term shrinkage variability. The yarn shrinkage differential (hereinafter also designated by the symbol AS,,,,,,,") is determined by a test carried out on a skein of yarn, by relaxing the yarn in 240F. (115.6C.) steam and measuring its length, before and after relaxing it, under loads of 50 grams and 4300 grams, as described in detail below. The degree of variable lengthwise shrinkage is measured by the standard deviation (hereinafter also designated by the symbol 0') of the yarn as determined in a Shrinkage Variance Test carried out on three 7-inch (17.5 cm.) yarn sections taken at approximately 10 yards (9 meters) distance from one another along the length of the yarn. Each section is marked in segments at 0.2-inch (0.5-cm.) intervals and the shrinkage of each of the 02-inch (0.5-cm.) yarn segments is determined upon relaxation of the yarn in 240F. l 15.6C.) steam by examination of enlarged photographs of the yarn sections before and after the yarn is relaxed, as described in detail below.

The fibers comprising the yarn are discontinuous organic textile fibers. Ordinary textile denier fibers are quite acceptable for this purpose. The yarn is composed of high-shrinkage fibers and low-shrinkage fibers, which may be fibers of the same polymeric composition, or fibers of different composition. Useful fibers include synthetics such as polyamide, polyester, or acrylic fibers and natural fibers such as cotton or wool. Fiber length of the discontinuous fibers may vary considerably. In one preferred embodiment, the fibers comprising the yarn are acrylonitrile polymer fibers. In another preferred embodiment, the fibers comprising the yarn are blends of acrylonitrile polymer fibers and polyethylene terephthalate fibers. The yarn may also contain one or more continuous filaments of an organic polymer.

Preferably, the yarn shrinkage differential (AS,,,,,,,) is at least 8 percent. In a highly preferred embodiment, the standard deviation is at least about 4.

In the process of the present invention:

A sliver is formed of discontinuous organic textile fibers containing from 1 to 40 percent of high-shrinkage fibers, the remainder being low-shrinkage fibers. The high-shrinkage fibers of the sliver should have an average percent shrinkage that is equal to or greater than percent plus the average percent shrinkage of the low-shrinkage fibers. The fibers in the sliver should preferably be of various lengths, the preponderance of the fibers ranging from about 2 to about inches or more in length. The sliver is then drafted to form a ribbon-shaped bundle of at least 30 denier and substantially free of twist. The bundle is sucked from the front drafting rolls by means of an aspirating jet of fluid, and false twisted to form the fasciated yarn by feeding through a torque jet and collecting said yarn.

It is preferred that the high-shrinkage fiber have an average shrinkage of at least 10 percent plus the average percent shrinkage of the low-shrinkage fibers. In a highly preferred embodiment of the process, the highshrinkage fibers comprise from 4 to 16 percent of the sliver. Shrinkage of the fiber in the sliver is determined in accordance with the Boil-Off Shrinkage Test described in detail below.

DESCRIPTION. OF TESTS The following tests are employed in measuring the parameters of a yarn to ascertain whether the yarn is the novel yarn product of the present invention.

YARN SHRINKAGE DIFFERENTIAL TEST FOR DETERMINING AS In this test, a skein of yarn is prepared and relaxed free of tension, as described in detail below. A calculation is made of its percentage shrinkage, based on length measurements under light load, before and after relaxation under no load. A second calculation is then made of its percentage shrinkage, based on measurements made under heavy load, before and after relaxation under no load. The difference between the two percent shrinkage values is designated as the yarn shrinkage differential. This test is designed to detect the presence of high-shrinkage fibers in the yarn and provides an indication of their concentration.

In carrying out this test, a skein is prepared by winding the yarn sample on a reel to form a loop of yarn having a circumference of approximately 136 cm. The number of turns of the reel required to form the loop is adjusted to yield a loop of approximately 6,030 denier (sum of the deniers of all of the turns of yarn in the loop); in the case of 90.0 denier yarn, 67 turns of the reel are required. The ends of the yarn forming the loop are tied together and small pieces of string are tied loosely about the loop at three places around its circumference to hold it together. The skein is hung from a hook by placing the inside of the loop over the hook. A hooked load is hung from the bottom of the loop, and the distance between the two hooks is designated herein as the length of the skein (initially about 68 cm. under light load). The initial length of the skein is measured under a load of 50 grams and this measurement is recorded and designated as L The initial length of the skein is then measured again under a load of 4300 grams and this measurement is recorded and designated as 13 The load is then removed and the skein is shrunk by relaxing it, free of tension, in an autoclave by subjecting the skein to 4 minutes of vacuum followed by 20 minutes exposure to steam at a temperature of 240F. (l 15.6C.) and a pressure of 10 psi gauge 1.7 kg./cm. absolute) and then finally by an additional 4 minutes of vacuum. After the skein is relaxed, its length under a load of 50 grams is then first measured and this length is recorded and designated as L then finally its length under a load of 4300 grams is measured and this length is recorded and designated as L The percentage shrinkage under a load of 50 grams (S the percentage shrinkage under a load of 4300 grams (S and the yarn shrinkage differential AS m-n are then calculated according to the following equations:

In the examples which follow, 10 skeins are employed in this test and the average yarn shrinkage differential of the 10 skeins is calculated.

SHRINKAGE VARIANCE TEST FOR DETERMINING STANDARD DEVIATION (0) OF YARN Three yarn sections from the same yarn specimen, having a length of approximately 8 inches (20 cm.) each, are fastened under substantially zero tension, with tape at both yarn ends on a flat steel plate, parallel to one another. The three yarn sections are taken at X 10 yards (9 meters) distance from one another along the length of the yarn. Each yarn is marked at 0.2-inch (0.5-cm.) intervals with a sharp charcoal pencil over a length of 7 inches (17.5 cm.), resulting in 35 yarn segments for each of the three yarn sections or a total of segments of 0.2-inch (0.5-cm.) length for each test yarn. The yarns are then placed under a microscope and photographs are taken of each segment at 20X magnification. With suitable spacing of the yarns on the steel plate, three segments located on each of three adjacent yarn sections can be taken on a single photograph. After photographs are taken of all 105 segments, the yarns are unfastened from the steel plate at one end to permit free shrinkage in the subsequent heat-setting step. The steel plate is then placed in a heat-setting apparatus and the setting step is carried out by exposing the yarns to 4 minutes of vacuum followed by 20 minutes of exposure to steam at a temperature of 240F. (115.6C.) and a pressure of 10 psi gauge (1.7 kg./cm. absolute) and a final exposure to 4 minutes of vacuum.

After the yarns are heat-set, the loose end of each yarn is taped again to the steel plate under substantially zero tension, but making sure that each yarn is straight. The yarns are again placed under a microscope and photographs are again taken of each segment at 20X magnification. The length of each 0.2-inch (0.5-cm.) yarn segment is measured on the photographs taken before and after shrinking, and the percent shrinkage is calculated for each individual 0.2-inch (0.5-cm.) yarn segment. The Mean Value of the percent shrinkages of the individual yarn segments and the standard devia- Mean Value Ex/n and where x the percent shrinkage of individual 0.2-inch (0.5-cm.) yarn segments and n the number of observations (105 in this instance).

The shrinkage of individual fibers taken from slivers as fiber samples is determined by the Boil-Off Shrinkage Test, as defined below.

BOIL-OFF SHRINKAGE TEST In this test a fiber, preferably at least 1.5 inches (3.8 cm.) in length, is conditioned for 20 minutes in air at 7090F. (21.1 322C.) and then is placed in moving air at 70F. i 2F. (21.1C. i 1.1C.) and 65 percent (:t 2 percent) relative humidity for a minimum of 16 hours. The initial length of the fiber (A) is measured and the fiber is then submerged, free of tension, in boiling water at atmospheric pressure for minutes (i 1 minute). The fiber is conditioned again and the final length of the fiber (B) is then measured. Percent shrinkage is calculated according to the equation:

% Shrinkage (A B)/(A) X 100%.

At least 10 fibers representative of the group of high shrinkage fibers or of the group of low-shrinkage fibers should be measured and the average shrinkage calculated.

It should be understood that preparation of the fasciated yarn of the invention may involve subjecting the fibers to conditions which alter their shrinkage. This factor should be taken into account in selecting fibers to meet the requirement of at least a 5 percent difference in average shrinkage FABRIC RATINGS In evaluating fabrics prepared as described in the examples below with regard to their crepe characteristics, the following ratings are employed:

Very Pronounced Fabrics characterized by a very high degree of crepe.

Pronounced Fabrics characterized by a high degree of crepe.

Moderate Fabrics characterized by an intermediate degree of crepe.

Subtle Fabrics characterized by a relatively low to border-line degree of crepe.

Slight Fabrics characterized by a borderline to very low degree of crepe.

Very Slight Fabrics characterized by a very low degree of crepe; too low for reproducible commercial fabrics having a crepe effect readily distinguished from conventional flat fabrics which contain defects.

In the examples below, the degree of crepe effect obtained at various percentage contents of high-shrinkage fiber, using starting material fibers having a difference in shrinkage of about 13-14 percent, is illustrated in the first two examples. Example 111 is a comparison between the novel, mixed-shrinkage fasciated yarns of this invention and conventionally spun yarns made of the same fibers in the same proportions, showing that the novel yarns lead to crepe fabrics while the conventional yarns do not. Example IV illustrates the degree of crepe effect obtained at various percentage contents of high-shrinkage fiber, using starting material fibers having a difference in shrinkage of only about 8 percent, while Example V illustrates yarns made from starting material fibers having a difierence in shrinkage of about 28 percent. Examples VI, VIII and IX illustrate yarns made from mixtures of various polyester and acrylic fibers, while Example VII shows a yarn made of bicomponent acrylic fibers.

EXAMPLE I A 470,000-denier tow of filaments of 2-denier per filament acrylonitrile/methyl acrylate/sodium styrenesulfonate (94/5.8/0.2) terpolymer is stretch-broken on a conventional stapling machine (the Turbo Stapler, manufactured by the Turbo Machine Company, Lansdale, Pa.) to produce a 115-grain per yard (73,400- denier) silver. The plate temperature is 325F. (162.8C.), the draw ratio is 2.38, the ratch setting is 12 inches (30.5 cm.), and the draft is 2.73. The fibers in the resulting sliver have a denier per filament of 0.99 and a boil-off shrinkage of 15.26 percent. This sliver is designated below as Sliver I-H".

Another portion of the tow is stretch-broken under the same conditions, except that the ratch setting is 13 inches (33 cm.). The sliver so produced is relaxed in an autoclave (Turbo Fiber Setter, manufactured by the Turbo Machine Company) in a treatment involving 4 minutes vacuum followed by 20 minutes exposure to 240F. (115.6C.) steam at 10 psi gauge (1.7 kg./cm. absolute), with a final 10 minutes vacuum treatment.

The fibers in the resulting sliver have a denier per filament of 1.09 and a boil-off shrinkage of 2.40 percent. This sliver is designated below as Sliver I-L and has a weight of 148 grains per yard (94,400 denier).

From the shrinkage values above, it is calculated that the fibers in Sliver I-H have an average shrinkage 12.86 percent greater than the average shrinkage of the lowshrinkage fibers.

A series of slivers is then formed by combining, in each instance, a total of 16 ends of the above slivers on a conventional rebreaker (the Gastonia Rebreak Machine, made by the Gastonia Roller, Flyer & Spindle Co., Inc., of Gastonia, NC, modified to accommodate a longer ratch and equipped with aprons), using a ratch setting of 13.5 inches (34.3 cm.), to produce approximately -grain per yard (64,000-denier) slivers containing various proportions of highand low-shrinkage staple fibers. In the first sliver, all 16 ends of the feed sliver are Sliver l-L. The second sliver is prepared by blending two ends of Sliver I-I-I with 14 ends of Sliver I-L on the rebreaker to produce a mixed-shrinkage sliver containing 10.0 percent of the high-shrinkage fiber. Other slivers are produced in which 3, 4, 5, 6, 8, and all 16 of the 16 ends combined on the rebreaker are Sliver I-I-1, the proportion of high-shrinkage fiber in each of these slivers being 15.2, 20.6, 26.0, 31.8, 44.0, and 100 percent, respectively.

Fasciated yarns are prepared from each of the above combined slivers processed on the rebreaker, employing the high-speed drafting process as shown in FIG. 4 of US. Pat. No. 3,438,094 to F. C. Field, Jr. A draft of 19.01 is employed between the pair of rolls 32 and 33 and the pair of rolls 38 and 39. A draft of 37.54 is employed between the pair of rolls 38 and 39 and the pair of front drafting rolls 30 and 31 to yield a ribbon shaped bundle. Roll 31 is of the cage design as shown in FIGS. 2A and 2B and discussed in Examples 11 and III of US. Pat. No. 3,438,094. The yarn velocity at wind-up is 400 yards per minute (366 meters per minute). The jet 41 is the aspirating jet shown in FIG. 3 of Fields earlier patent, US. Pat. No. 3,079,746, except that the yarn passage from inlet to outlet is of uniform diameter. Air is supplied through fluid tube 31 of the aspirating jet at a pressure sufficient to ensure removal of the fibers from the cage roll nip. The jet 42 is a torque jet having a yarn passageway 1/16 inch (0.158 cm.) in diameter, similar to the torque jet shown in FIG. 4 of US. Pat. No. 3,079,746, employing superheated steam at a temperature of 450F. (232.2C.) and a pressure of 150 psi gauge (11.6 kg./cm. absolute) as the fluid medium. The tension between the cage rolls and the windup is maintained in the range of 3 to 9 grams. The properties of the fasciated yarns so produced are listed in Table 1.

Four sets of broadwoven fabrics are prepared, the warp yarn in the first set being the fasciated yarn having percent high-shrinkage fiber content; the warp yarn in the second set being the yarn containing 20.6 percent high-shrinkage fiber; the warp yarn in the third set being the yarn containing 44 percent high-shrinkage fiber; and the warp yarn in the fourth set containing 100 percent high-shrinkage fibers. In each set, eight fabrics are produced, one for each of the eight fasciated yarns used as the filling yarn in the fabric. The fabrics have a 1X1 plain weave fabric construction in the loom of 120 ends per inch (47 ends/cm.) in the warp by 70 picks per inch (28 picks/cm.) in the filling: except for the fourth set of fabrics, which have a construction in the loom of 120 ends per inch (47 ends/cm.) in the warp by 55 picks per inch (22 picks/cm.) in the filling. In the finishing sequence the woven fabrics are singed, desized, and dyed in the beck at the boil for approximately 2 hours, after which the crepe can be seen. Finally, the fabrics are frame dried under relaxed conditions and cold calendered.

The fabrics are rated in accordance with the degree of crepe effect apparent in the fabric using the crepe intensity definitions outlined above. In all four sets of fabrics, produced with four different warp yarns, it is observed that the degree of crepe effect is highly dependent upon the filling yarn. Fabrics containing the same filling yarn, but different warp yarn, exhibit the same degree of crepe; and ranking and rating of crepe appearance for each filling yarn is therefore the same in each of the four different warp yarns. Accordingly, the ratings of the fabrics are given in Table l as a single set of ratings for each filling yarn, equally valid for each of the four warp yarns used.

In view of the above observation, a common warp yarn is employed in preparing all fabrics in Examples ll through IX.

8 EXAMPLE II A quantity of the tow employed in Example I is converted to an approximately 1 l7-grain per yard (74,600 denier) sliver on a stapling machine, within which the tow is passed between plates heated to 325F. (162.8C.) and drawn at a draw ratio of 2.38 and then stretch-broken at a ratch setting of 14 inches (35.6 cm.). The draft is 2.73. The fibers in the resulting sliver have a denier per filament of 1.01 and a boil-off shrinkage of 14.5 percent. This sliver is designated below as Sliver lI-H.

One portion of Sliver 11-11 is relaxed in an autoclave as in Example I, except that 236.5F. (1 136C.) steam is at 8.7 psi gauge (1.6 kg./cm. absolute) is used in this instance; after which 12 ends of the sliver are blended on a rebreaker at a ratch setting of 13.5 inches (34.3 cm.) to form an approximately IOO-grain per yard (64,000 denier) sliver. The fibers in the sliver have a denier per filament of 1.26 and a boil-off shrinkage of 0.21 percent. This sliver is designated below as Sliver ll-L.

The starting material fibers in this example, as shown above, have properties similar to but not identical with 2 the starting material fibers of Example I, illustrating 14.29 percent greater than the average shrinkage of the low-shrinkage fibers.

Eleven ends of Sliver ll-L are then blended with one end of Sliver ll-H on a rebreaker to produce an approximately l00-grain per yard (64,000 denier) sliver containing 9.6 percent of the high-shrinkage fiber, designated below as the 9.6% Sliver. Other slivers are similarly produced from a total of 12 ends of sliver in which 0, 2, 4, and all 12 of the 12 ends combined on the rebreaker are Sliver ll-l-I, the proportion of highshrinkage fiber in each of these slivers being 0, 19, 36.9, and 100 percent, respectively. Additional slivers are produced by blending ends of the 9.6 percent Sliver with ends of Sliver II-L in the following ratios to form slivers containing low proportions of the highshrinkage fiber); and 6 to 6 (4.8 percent high-shrinkage fiber).

A set of fasicated yarns is then prepared from each of the above-described combined slivers, using the procedure for preparing fasciated yarns described in Example 1, except that the first draft is 25.16; the second draft is 28.06; and the 450F. (232.2C.) superheated steam employed in the torque jet is at a pressure of RICS MADE 'IIIE RF. F ROM lligh-slninku w fiber content, percent 0 10.0 15. 2 20. 6 10.0 -14. 0 100.0

Yarn denier 89 89 89 U3 U0 1. J1 12 Yarn shrinkage differential test:

7. .2 12. 1 15.3 14.0 15. 9 l7. 2 If). 4 1). 8

Fabric crepe rating 1 NOlll. 3 Pronounced. 3 Moderate. 1 Subtle. Slight. 6 \cry slight.

psi gauge (11.2 kg./cm. absolute). The properties of the fasciated yarns so produced are listed in Table 2.

A set of broadwoven fabrics is prepared containing one fabric made from each of the above fasicated yarns used as a filling yarn. The fabrics have a 1X1 plain weave fabric construction in the loom of 120 ends per inch (47 ends/cm.) in the warp by 60 picks per inch (23.5 ends/cm.) in the filling. The finishing sequence is the same as employed in Example I. The fabrics are rated with regard to the degree of crepe effect apparent in the fabric. The ratings of the fabrics are also given. in Table 2.

The warp yarn used to prepare the above fabrics is, in each instance, a fasciated yarn containing 9.6 percent of the high-shrinkage fiber made in quantity according to the procedure described above.

taining 5.8 percent of the high-shrinkage staple fiber. Similarly, an approximately IOO-grain per yard sliver containing 12.0 percent of the high-shrinkage staple fiber is produced by blending 10 ends of Sliver III-L and 2 ends of Sliver III-H on the rebreaker; and an approximately 100-grain per yard sliver containing 25.5 percent of the high-shrinkage fiber is produced by blending 8 ends of Sliver III-L and 4 ends of Sliver III-H on the rebreaker. A set of fasciated yarns is then prepared from each of these slivers as in Example I.

A set of three conventional spun yarns is also prepared from the 3 slivers of mixed-shrinkage fibers, employing conventional worsted system spinning apparatus. The preparation of this yarn involves one additional pass on the rebreaker, 6 pin drafting passes, rov- .ing, and spinning on a worsted frame. The resulting TABLE 2.PROPE RTIES OF FILLING YARNS OF EXAMPLE H AND FABRICS MADE THE REFROM High shrinkage fiber content, percent 0.8 1.6 2.4 4. 8 9.6 19.0 36.9 100.0 Yarn denier 90 90 90 90 92 94 92 95 105 Yarn shrinkage differential test:

5.8 0.0 12.3 14.1 10.3 18.1 20.5 22.8 19.8 .52 .1: 1%; 21 shrink e vaiiance test: I 1 l I 1 Mean value 12.1 12.1 15.3 2.1 1% 0' J Fabric crepe rating None (Y) None I Slight. 2 Moderate. 3 Pronounees. 4 Subtle.

EXAMPLE n yarliiis gre 60 cc. (89 denier yarns with 252 turns per inc .8 turns er cm. twist.

A low-shrinkage sliver of conventional white acrylic 2 proper; of bo)th the fasciated yams and the fibers is prepared as in Example I, employing the same conventionally spun yams are listed in Table 3 starting material tow, stapling machine settings, and red f h f laxing conditions. After relaxing, it is found to be a A set of brofidwoven P F prepare Tom eac l48-grain per yard (94,400-denier) sliver of fibers hav- F three fasclated f m this example as a mg a denier per filament of 1.23 and a boiloff Shrink mg yarn, together with a control set of fabrics woven age of 0.04 percent It is designated as Sliver from each of the three conventionally spun yarns pro- A 470,000-denier tow of 3-denier per filament, black ducefd as descflbed above us,ed as a finmg The (carbon black added to the spinning solution) acrylic fabric construction and finishing sequence are the same filaments of the same terpolymer is stretch-broken on 40 as i g fabncs are rated m the stapling machine under the same conditions, except cordanc? t egfee 0 pe effect apparent n that the draw ratio is 252 to produce a l01 grain per the fabric. The ratings of the fabrics are also given in yard sliver (64,400-denier). This sliver, designated Table below as Sliver III-H, is not subjected to steam relax- The warp yarn used to prepare the above fabncs 1s, ation. The fibers in this sliver have a denier per filament in each instance, a fasciated yarn made in quantity acof 1.16 and a boil-off shrinkage of 14.6 percent.

From the shrinkage values above, it is calculated that cording to the procedure described for the yarn containing 9.6 percent high-shrinkage fiber in Example II.

' IABLE s.1 RoPn R'rIEs OF FILLING YARNS OF EXAMPLE in AND FABRICS MADE THEREFROM Conventionally spun Fasciatetl Yarns yarns High shrinkage fiber content, pmcenL... 5.8 12.0 25. 5 5.8 12.0 25. 5 Yam denier 92 J3 113 .10 10 10 Yarn shrinkage (liilm'ential test:

S 16. 5 l8. 7 10. 1 14. (i 17. 2 20. 7 ,300 2. El 5. 1'1 1'2. 3 7. 4 J. 2 13.0 A b 13.6 13.1 7.1) 7. 2 8. I) 7.1 Shrinkage v:

Ml'un value... 11.7 14.2 14.2 12.2 13.7 16.0 I1... M 7.0 6.0 4.! 2.1 2.3 2.7 l'uln'iu err-p0 rating" None None N01 1 l'rmlouneuil. 2 lvloderatv.

the fibers in Sliver III-H have an average shrinkage EXAMPLE Iv 14.56 percent greater than the average shrinkage of the low-shrinkage fibers.

Eleven ends of Sliver III-L and one end of Sliver III-H are blended on the rebreaker to produce an approxi mately IOO-grain per yard (64.000 denier) sliver con- (34.3 cm.). The fibers in the resulting sliver have a denier per filament of 1.91 and a boil-off shrinkage of 8.6 percent. It is an approximately 100-grain per yard (64,000 denier) sliver and is designated below as Sliver IV-l-l".

Using a total of 12 ends of sliver, combined slivers of mixed shrinkage are prepared on the rebreaker from appropriate quantities of Sliver IV-H blended with ends of Sliver Il-L. A series of slivers containing 0, 8.3, 16.7, 33.3, and 100 percent of the high-shrinkage fiber are prepared. A set of fasciated yarns is then prepared from each of these slivers as in Example 11. The properties of the fasciated yarns so produced are listed in Table 4.

From the shrinkage values of the fibers in the slivers, it is calculated that the fibers in Sliver IV-l-I have an average shrinkage 8.4 percent greater than the average shrinkage of the low-shrinkage fibers.

A set of broadwoven fabrics is prepared from each of the five fasciated yarns in this example used as a filling yarn. The fabric construction and finishing sequence are the same as employed in Example 11. The fabrics are rated in accordance with the degree of crepe effect apparent in the fabric. The ratings of the fabric are also given in Table 4.

The warp yarn used to prepare the above fabrics is, in each instance, a fasciated yam made in quantity according to the procedure described for the yarn containing 9.6 percent high-shrinkage fiber in Example 11.

TABLE 4.I ROERTIES OF FILLING YARNS 6F EXAMPLE IV AND FABRICS MADE THEREFROM lligh shrinkage fiber content, percent... 0

Yarn denier Yarn shrinkage differential test:

Mean value 0 Fabric crepe rating 3 Moderate.

1 None. 2 Pronounced. 4 Subtle.

EXAMPLE V A 470,000-denier tow of filaments of 3-denier per filament acrylonitrile/methyl acrylate/methylvinylpyridine (90.3/5.8/3.9) terpolymer is stretch-broken on a conventional stapling machine as in Example I, using a 300F. 148.9C.) plate temperature, draw ratio of 2.38, and a ratch setting of 13.5 inches (34.3 cm.) to produce an approximately 100-grain per yard (64,000 denier) sliver. The fibers in the sliver have a denier per filament of 1.50 and a boil-off shrinkage of 28.7 percent. This sliver is designated below as Sliver V-l-l.

Using a total of 12 ends of sliver, combined slivers of mixed shrinkage are prepared on the rebreaker from appropriate quantities of Sliver V-l-l blended with ends of Sliver ll-L. A series of slivers containing 0, 8.3, 16.7, 33.3, and 100 percent of the high-shrinkage fiber is prepared. A set of fasciated yarns is then prepared from each of these slivers as in Example 11. The properties of the fasciated yarns so produced are listed in Table 5.

From the shrinkage values of the fibers in the slivers, it is calculated that the fibers in Sliver V-H have an average shrinkage 28.5 percent greater than the average shrinkage of the fibers in Sliver Il-L.

A set of broadwoven fabrics is prepared from the five fasciated yarns in this example used as a filling yarn. The fabric construction and finishing sequence are the same as employed in Example 11. The fabrics are rated in accordance with the degree of crepe effect apparent in the fabric. The ratings of the fabrics are also given in Table 5.

TABLE Fir-PROPERTIES OF FILLING YARNS OF EXAMPLE V ANI) FABRICS MADE TIIEREFROM lligh shrinkage. Iiher content, percent... 0 8. 3 1G. 7 33. 3 mo Yarn denier H0 110 11'. U3 Yr. rn shrinkage differential H50 5. 8 30. 8 37. (I 41. l '11. .1 3 2. 5 3. 5 0. 7 34. (i 10.7 AS 3. 3 33. 3 28. 2 G. 8 0. 8 Shrinkage variance test:

Mean value 3. 3 2G. 7 .27. 4 32. 4 34. 1 0' 2. 1 8. 2 6. t 3. 9 1. Fabric crepe rating 1 None. 2 Very pronounced. 3 Pronounced. 4 Subtle.

EXAMPLE VI A 267,000-denier tow of filaments of 1.5-denier per filament polyethylene terephthalate is stretch-broken on a conventional stapling machine, using a draw ratio of 1.23 and a draft of 3.74 to produce an approximately -grain per yard (64,000 denier) sliver. The fibers in the sliver have a denier per filament of 1.40 and a boiloff shrinkage of 2.32 percent. This sliver is designated below as Sliver Vl-L.

Using a total of 12 ends of sliver, combined slivers of mixed shrinkage are prepared on the rebreaker from appropriate quantities of acrylic Sliver lI-H blended with ends of polyethylene terephthalate Sliver Vl-L above. A series of slivers containing 0, 9.6, 19.0, 36.9, and 100 percent of high-shrinkage fiber is prepared. A set of fasciated yarns is then prepared from each of these slivers as in Example 11. The properties of the fasciated yarns so produced are listed in Table 6.

From the shrinkage values of the fibers in the slivers, it is calculated that the fibers in Sliver Il-l-I have an average shrinkage 12.2 percent greater than the average shrinkage of the fibers in Sliver VI-L.

A set of broadwoven fabrics is prepared from each of the five fasciated yarns in this example used as a filling yarn. The fabric construction and finishing sequence are the same as employed in Example II. The fabrics are rated in accordance with the degree of crepe effect apparent in the fabric. The ratings of the fabrics are also given in Table 6.

The warp yarn used to prepare the above fabrics is, in each instance, a fasciated yarn made in quantity according to the procedure described for the yarn containing 9.6 percent high-shrinkage fiber in Example 11.

High shrinkage fiber content, peleent 0 0. 6 19.0 36. 9 100 Yarn denier 8O 90 90 E14 Yarn shrinkage differential test:

350 6. 1 14. 9 16. 8 1!). 1 19.8 St W 3. 7 5. 6 '1. o 15. 5 10.1 3. 2 0. 3 7. 8 3. 6 O. 7

1 Very slight. lronolnm-ll. 3 Moderate. 4 Slight. 5 None.

EXAMPLE V11 A 470,000-denier tow of bicomponent filaments having a denier of 3 per filament and composed of 57 per cent by weight of acrylonitrile/methyl acrylate/sodium styrenesulfonate (94/S.8/0.2) terpolymer as one component of the filament and 43 percent by weight of a blend of 90 percent acrylonitrile homopolymer and 10 percent of the acrylonitrile/methyl acrylate/sodium styrenesulfonate (94/58/02) terpolymer as the other component is stretch-broken on a conventional stapling machine. The draw ratio is 2.38. An approximately 100-grain per yard (64,000 denier) sliver of fibers having a denier per filament of 1.52 and a boil-off shrinkage of 15.1 percent is produced. This sliver is designated below as Sliver VII-H.

One portion of the bicomponent Sliver VII-H is relaxed in a commercial heat-setting apparatus as in Example The fibers in the resulting sliver have a denier per filament of 1.56 and a boil-off shrinkage of 0.41 percent. This sliver is designated below as Sliver VII- L and has a weight of approximately 150 grains per yard (96,000 denier).

From the shrinkage values above, it is calculated that the fibers in Sliver VII-H have an average shrinkage 14.7 percent greater than the average shrinkage of the fibers in Sliver VII-L.

A combined sliver of mixed shrinkage is then prepared from one end of Sliver VII-H and eleven ends of Sliver VII-L. This sliver contains 5.7 percent highshrinkage fiber. A fasciated yarn is then prepared from this sliver as in Example II. The fasciated yarn so produced has a denier of 129; an S of 15.6 percent, and S of 3.4 percent, with AS being 12.2 percent. In the shrinkage variance test, the Mean Value is 15.3 percent and the standard deviation, is 4.9. A broadwoven fabric is then prepared, using the fasciated yarn of this example as a filling yarn and a fasciated yarn made according to the procedure described for the yarn containing 9.6 percent high-shrinkage fiber in Example II as the warp yarn. The fabric construction and finishing sequence are the same as employed in Exam- .ple 11. It exhibits a pronounced degree of crepe.

EXAMPLE VIII A combined sliver of mixed shrinkage is prepared from one end of acrylic Sliver II-H, five ends of acrylic Sliver II-L, and six ends of polyester Sliver VI-L. This sliver contains 9.6 percent high-shrinkage fiber. A fasciated yarn is then prepared from this approximately 50 percent acrylic/50 percent polyester blend sliver as in Example II. The fasciated yarn so produced has a denier of 93, and S of 15.7 percent, an $4300 of 5.5 percent with AS being 10.2 percent. In the shrinkage variance test, The Mean Value is 13.1 percent and the standard deviation, 0', is 5.4, A broadwoven fabric is then prepared, using the fasciated yarn of this example as a filling yarn and a fasciated yarn made according to the procedure described for the yarn containing 9.6 percent high-shrinkage fiber in Example II as the warp yarn. The fabric construction and finishing sequence are the same as employed in Example II. It exhibits a pronounced degree of crepe.

EXAMPLE 1x 5 A combined sliver of mixed shrinkage is prepared from one end of acrylic bicomponent Sliver VII-H, five ends of acrylic bicomponent SIIVBYrYII-L, and six ends of polyester Sliver VI-I... This sliver -contains.6.9 percent high-shrinkage fiber. A fasciated yarn is then prepared from this approximately 60 percent acrylic/4O percent polyester blend sliver as in Example II. The fasicated yarn so produced has a denier of 1 18, an S of 15.4 percent, an S4300 of 5.0 percent with AS being 10.4 percent. In the shrinkage variance test, the Mean Value is 13.6 percent and the standard deviation, 0, is 5.7. A broadwoven fabric is then prepared, using the fasciated yarn of this example as a filling yarn and a fasciated yarn made according to the procedure described for the yarn containing 9.6 percent highshrinkage fiber in Example II as the warp yarn. The fabric construction and finishing sequence are the same as employed in Example II. It exhibits a pronounced degree of crepe.

What is claimed is:

l. A fasciated yarn comprising a core of discontinuous organic fibers bound together by discontinuous organic fibers disposed as an irregular helical wrapping around the core, said yarn exhibiting a yarn shrinkage differential, AS of at lest 5 percent and a standard deviation, 0', of at least 2.8 in short-term shrinkage variability.

2. The yarn of claim 1 wherein the fibers are acrylonitrile polymer fibers.

3. The yarn of claim 1 wherein the fibers are blends of acrylonitrile fibers and polyethylene terephthalate fibers.

4. The yarn of claim 1 wherein the yarn shrinkage differential is at least 8 percent and the standard deviation, 0', in short-term shrinkage variability is at least about 4.

5. A process of preparing a fasciated yarn suitable for the production of crepe fabrics comprising forming a strand of blended organic fibers of which from 1 to 40 percent by weight are high-shrinkage fibers having an average shrinkage that is at least 5 percent above that of the average of the remaining fibers, drafting said strand to form a ribbon-shaped bundle, said bundle comprising discontinuous fibers and being substantially free of twist, sucking said ribbon-shaped bundle from the front drafting rolls by means of an aspirating jet of fluid and false-twisting said bundle into a yarn by feeding through a torque jet wherein discontinuous fibers of the bundle are wrapped as irregular helices around discontinuous fibers of the bundle which constitutes the core of the yarn and collecting said yarn.

6. The process of claim 5 wherein the fibers comprising the yarn are acrylonitrile polymer fibers.

7. The process of claim 5 wherein the fibers comprising the yarn are a blend of acrylonitrile polymer fibers and polyethylene terephthalate fibers.

8. The process of claim 5 wherein the high-shrinkage fibers have an average shrinkage that is at least 10 percent above that of the remaining fibers.

9. The process of claim 5 wherein the high-shrinkage fibers comprise from 4 to 16 percent by weight of the yarn. 

2. The yarn of claim 1 wherein the fibers are acrylonitrile polymer fibers.
 3. The yarn of claim 1 wherein the fibers are blends of acrylonitrile fibers and polyethylene terephthalate fibers.
 4. The yarn of claim 1 wherein the yarn shrinkage differential is at least 8 percent and the standard deviation, sigma , in short-term shriNkage variability is at least about
 4. 5. A process of preparing a fasciated yarn suitable for the production of crepe fabrics comprising forming a strand of blended organic fibers of which from 1 to 40 percent by weight are high-shrinkage fibers having an average shrinkage that is at least 5 percent above that of the average of the remaining fibers, drafting said strand to form a ribbon-shaped bundle, said bundle comprising discontinuous fibers and being substantially free of twist, sucking said ribbon-shaped bundle from the front drafting rolls by means of an aspirating jet of fluid and false-twisting said bundle into a yarn by feeding through a torque jet wherein discontinuous fibers of the bundle are wrapped as irregular helices around discontinuous fibers of the bundle which constitutes the core of the yarn and collecting said yarn.
 6. The process of claim 5 wherein the fibers comprising the yarn are acrylonitrile polymer fibers.
 7. The process of claim 5 wherein the fibers comprising the yarn are a blend of acrylonitrile polymer fibers and polyethylene terephthalate fibers.
 8. The process of claim 5 wherein the high-shrinkage fibers have an average shrinkage that is at least 10 percent above that of the remaining fibers.
 9. The process of claim 5 wherein the high-shrinkage fibers comprise from 4 to 16 percent by weight of the yarn. 